I've been noticing that I become horny during my period. Can menstruation really affect my libido?

Many women report an increase in libido during their period, though the jury is still out on the exact reasons why. It might have to do with fluctuating hormones, which tend to be high during ovulation and low during menstruation. It's possible that you're in an amorous mood because PMS is alleviated by the onset of your period. Or, you could feel sexier due to increased blood flow and lubrication in your below-the-belt region. Another theory: Maybe you're more relaxed with sex at this point of your cycle because you're less likely to become pregnant (though experts say there is still a slim chance that it could happen). It could also be a combination of any of these.

Since libido and hormonal changes vary from month to month  and from woman to woman  the reasons why you feel more randy at certain times probably vary as well. Just enjoy the fact that you've got a healthy sex drive and try to make the most of it. If you and/or your guy are a little squeamish about doing the deed when you're menstruating, you can always use a cervical cap, diaphragm, or menstrual cup to avoid any messiness.